1. Field of the Invention
The present invention relates to a mono carbonylation process of benzene diols, and in particular to a process for mono carbonylation of benzene diols which is characterized in that a mono protected benzene diol is prepared in high yield by reacting hydroquinone with acid anhydride or carbonylhalide without any bases in accordance with a protective reaction of hydroquinone which is widely used in a fine chemical industry.
2. Description of the Background Art
Benzene diol has two equivalent hydroxyl groups, so it is hard to adapt a substitutent selectively. In particular, mono acetyl hydroquinone is a compound (Korean patent application No. 2000-27129, U.S. patent application Ser. No. 09/838,841) which is an important intermediate for preparing arbutin used as a whitening agent. Therefore, mono carbonylated benzene diols are useful for preparing an asymmetrically substituted benzene diol derivative which is industrially useful.
As an example of mono carbonylation of benzene diol, various processes are known as follows for a process for mono acetylation of hydroquinone.    1. Eur. Pat. Ep 178,929B, Celenase company    2. Eur. Pat. Ep 167,464B, Rhone-Pounenc company    3. Chem. Ind. (London), 1982, (24), 1000 Stering-Winthrop company
The process (1) of Celenase company is characterized in that 4-acetyl phenol is synthesized by the Fries rearrangement of phenyl acetate prepared from the acetylation of phenol and it is oxidized with hydrogen peroxide by “Baeyer-Villiger” reaction to synthesize 4-acetyl hydroquinone. In the above process, hydrogen fluoride which is hard to handle in the Fries rearrangement reaction is used, and the yield of oxidation is below 60%.
The process (2) of Rhone-Poulenc company is characterized in that mono acetyl hydroquinone is synthesized by the ester interchange between hydroquinone and an excessive amount of diacetyl hydroquinone. However, It is not easy for separating excess diacetyl hydroquinone in the industrial process.
The process (3) of Stering-Winthrop company is characterized in that hydroquinone is reacted with acid anhydride in the presence of an organic base. Since hydroquinone has two equivalent hydroxyl groups, in case of monoacylation of hydroquinone, if one use a general method of acylation, monoacylated compounds are produced, the yield is low due to the excess production of diacylated hydroquinone and by the reaction with the acids resulted from using the organic bases, a salt can be produced. To remove the salt, it should be washed using water, so that a large amount of waste water is produced.
As described above, the above described processes are not proper for preparing mono carbonylated benzene diol in both economical and industrial basis.